This invention relates to the production of coke in a non-recovery type coke oven, and more particularly to a method for operating such a coke oven at an increased coking rate without polluting the atmosphere with effluents including products of distillation liberated from a coal charge during the coking process.
A non-recovery type coke oven is sometimes identified in the art as a beehive coke oven. In the past, a battery of such coke ovens were built adjacent each other and operated by pulling from alternative ovens on alternative days the masses of coke. The heat from the side walls of a hot coke oven and any residual heat retained in a newly-charged coke oven is usually sufficient to ignite the coal in the newly-charged coke oven. The cycle for production of coke by each oven chamber was about 72 hours. A non-recovery type coking process provides important features and advantages to the coking industry, particularly a more economical process for producing coke. The coke ovens used in a non-recovery type coking process are less costly and require a minimum of ancillary equipment, particularly because facilities are not required for treating by-products of the coking process. Non-recovery, beehive-type coke ovens in the past were capable of providing only a relatively low coke output per oven chamber. However, smoke together with other unburnt volatile products escape during the coking process into the atmosphere. The emissions are a source of environmental pollution whereby non-recovery type coking processes have been largely done away with in view of current environmental standards.
The chief method for producing coke currently is by a by-product or retort process wherein air is excluded from the coking chamber and all volatile products liberated during the distillation process are recovered as gas and other coal by-product chemicals. Many coking installations using the retort process still discharge unacceptable quantities of polluting gases into the atmosphere. Usually, the sale of chemicals recovered from the retort process was a source of income, but the sale of such chemicals has become increasingly less profitable.
In my U.S. Pat. No. 4,045,299, entitled "Smokeless Non-Recovery Type Coke Oven", there is disclosed a smokeless non-recovery type coke oven wherein the distillation gases liberated during the coking process are conducted from the space above the coal charge downwardly along passageways in the side walls forming the oven chamber into a sole heating flue. Primary air is fed into the oven chamber to maintain combustion within the space above the coal charge. Secondary air is fed into the downcomers to facilitate combustion of the gases in the sole heating flues and in a tandem arrangement of ignition chambers located downstream therefrom. Additional quantities of secondary air for combustion were injected into the ignition chambers and a burner is used to maintain a predetermined minimum temperature at all times in the ignition chamber to insure incineration of all smoke gases passing therethrough. The waste gases are conducted from the ignition chambers by a horizontal conduit to a stack. The arrangement of parts forming the coke oven chamber are intended to overcome poor and inefficient secondary combustion of the distillation products in the sole heating flues and the passageways within the walls of the coke oven chamber. The secondary combustion did not incinerate the distillation products but represented only a partial combustion thereof. The temperature within the ignition chambers was maintained at a minimum temperature of, for example, 1400.degree. F. for incinerating all the gases reaching this point before the gases were passed to the stack. The smokeless operation of the coke oven was significantly enhanced to the extent that emissions from the stack were found to be within acceptable standards.
I have now discovered an automatic control for the coking process when carrier out in a smokeless non-recovery type coke oven of the type disclosed in my aforesaid patent application will not only increase the rate at which coke is produced in the oven chamber but also further reduces emissions during the operation of the coke oven.